U.S. patent number 5,663,230 [Application Number 08/388,714] was granted by the patent office on 1997-09-02 for water stop composition and methods of preparing same.
This patent grant is currently assigned to Concrete Sealants, Inc.. Invention is credited to Robert J. Haman.
United States Patent |
5,663,230 |
Haman |
September 2, 1997 |
Water stop composition and methods of preparing same
Abstract
Water stop compositions and methods of preparing same are
disclosed. The compositions exhibit a controlled swelling or
volumetric expansion upon immersion in water. The compositions
swell about 5-8% after 1 day's immersion and about 35-65% after 28
day's immersion. A blend of fast acting sodium bentonite clay and a
slower acting calcium bentonite clay contribute to this desirable
controlled expansion along with a specific combination of
thermoplastic elastomer, cross-linked butyl rubber components and
polyisobutylene. Another important factor in providing the desired
expansion is a thorough mixing step to ensure product homogeneity
whereby mix components are blended in a Sigma mixer for an excess
period of time after all components have been added to the mixer.
An exemplary water stop composition includes about 10-30 wt %
elastomer, about 15-30 wt % filler, about 20-40 wt % plasticizer,
and about 25-35 wt % water swellable clay, the foregoing
percentages adding up to 100 wt %. The water swellable clay
preferably includes 40-50 wt % sodium bentonite clay, with the
remainder consisting of calcium bentonite clay.
Inventors: |
Haman; Robert J. (New Carlisle,
OH) |
Assignee: |
Concrete Sealants, Inc. (New
Carlisle, OH)
|
Family
ID: |
23535212 |
Appl.
No.: |
08/388,714 |
Filed: |
February 15, 1995 |
Current U.S.
Class: |
524/447; 524/445;
525/98 |
Current CPC
Class: |
C08K
3/346 (20130101); C08K 5/0016 (20130101); C08L
53/025 (20130101); C08K 3/346 (20130101); C08L
23/22 (20130101); C08K 5/0016 (20130101); C08L
23/22 (20130101) |
Current International
Class: |
C08K
3/00 (20060101); C08K 3/34 (20060101); C08L
53/02 (20060101); C08L 53/00 (20060101); C08K
5/00 (20060101); C08J 005/10 (); C08K 003/34 ();
C08L 053/02 () |
Field of
Search: |
;525/98
;524/445,442,447,448,451 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Chemical Abstracts, vol. 99,1983, p. 28-99:195819y Effect Of
Bentonite Or Rheological And Mechanical Properties Of
Polypropylene. .
Brochure "An Introduction To Vistanex LM Low Molecular Weight
Polyisobutylene", Exxon Chamical Company USA. .
Hardman Inc. Material Safety Data Sheet for Kalar 5263, pp. 1-4,
Jan. 29, 1991. .
Pfizer Inc. Material Safety. Data Sheet for Microtalc--Montana
Talc, Rev. 2, pp. 1-5, Jun., 1988. .
United Clays Inc. Material Safety Data Sheet for product 101, pp.
1-4, May, 1991. .
Product Fact Sheet Vistanex MM Polyisoburylene, Jul. 1, 1991 Exxon
Chemical Polymers Group. .
Union Camp Chemcentral/Cincinnati for Unitol AFL pp. 1-5, Aug. 5,
1991. .
Product Fact Sheet Vistanex LM Polyisobutylene--Vistanex
LM--Regular Grades, Dec., 1992. .
Exxon Chemical Company Polymers Group Material Safety Data Sheet
for Vistanex LM, pp. 1-4, Jul. 21, 1993. .
Brochure Vistanex Polyisobutylene Properties And Applications,
Exxon Chemical Company, Copyright 1993. .
Material Safety Data Sheet--Central Fiber Corporation for
Cellulosic Based Fibers, pp. 1-3, Jan. 1994. .
Shell Environmental Data Sheet for Shellvis(R) 40 Viscosity Index
Improver, pp. 1-5, Apr. 8, 1988. .
Southern Clay Products, Inc. Material Safety Data Sheet for
Bentolite L-10, Apr. 25, 1994. .
Southern Clay Products, Inc. Material Safety Date Sheet for Astra
Ben 5, Apr. 27, 1994. .
Miles Material Safety Data Sheet for Polysar BUTYL XL 10000, pp.
1-6, Apr. 1, 1994. .
WITCO Material Safety Data Sheet for Kendex 0842, pp. 1-3. .
Product Fact Sheet Kendex Industrial Products, Kendall/Amalie, Div.
of Witco Corp. for Kendex 0842..
|
Primary Examiner: Michl; Paul R.
Assistant Examiner: Rajguru; U. K.
Attorney, Agent or Firm: Biebel & French
Claims
What is claimed is:
1. Moisture swellable water stop composition comprising about 10-30
wt % elastomer, about 15-30 wt % filler, about 20-40 wt % process
oil plasticizer, and about 25-35 wt % water swellable bentonite
clay, said bentonite clay comprising a mixture of a high swelling
capacity sodium bentonite clay and a lower swelling capacity
calcium bentonite clay.
2. Water stop composition as recited in claim 1 wherein said high
swelling capacity sodium bentonite clay is present in an amount of
about 40-50% by weight based upon the weight of said mixture of
bentonite clay said water stop composition exhibiting a volumetric
expansion of not more than about 65% after 28 days immersion in
water.
3. Water stop composition as recited in claim 1 wherein said
elastomer comprises a thermoplastic elastomer.
4. Water stop composition as recited in claim 3 wherein said
thermoplastic elastomer comprises a styrene-ethylene/propylene
block copolymer.
5. Water stop composition as recited in claim 1 wherein said
elastomer comprises a thermoplastic elastomer, a cross-linked butyl
rubber component, and a polyisobutylene polymer.
6. Water stop composition as recited in claim 5 wherein said
cross-linked butyl rubber is present in an amount of about 10-20 wt
% of the total elastomer present.
7. Water stop composition as recited in claim 1 exhibiting a
volumetric expansion of about 5-8% after 24 hours immersion in
water and between about 35-65% expansion after about 28 days
immersion in water, said composition after 28 days immersion in
water, exhibiting substantially no cracking and being substantially
integral and intact.
Description
FIELD OF THE INVENTION
The present invention pertains to water stop compositions and
methods of preparing same.
BACKGROUND
Water stop compositions are normally extruded in the form of
elongated ropes or tapes and are typically used as a gasket or seal
in the joints or gaps between adjacent concrete or metallic
building panels or structure. A variety of rubber, plastic, and
asphalt water stop compositions have been used throughout the
years.
Desirably, the water stop should be swellable so that upon
hydrolysis it will expand to cover the surface area of the joint or
gap in which it is placed. In this manner, the water stop can then
adequately perform its intended function of acting as a water seal
to prevent water penetration into the gap or joint.
To this end, a variety of compositions including water soluble
clays, such as the bentonites, and a plurality of elastomeric
materials has been proposed. For example, U.S. Pat. No. 4,668,724
discloses water stop compositions comprising non-hydrated bentonite
clay contacted with a polypropene and/or polybutene tackifier.
Purportedly, the polypropene an/or polybutene tackifiers increase
the swelling capacity of the bentonite while providing sufficient
tack or adherence characteristics to the water stop.
European Patent Application 0 037 717 discloses an aqueously
swelling water stopping composition which comprises polyisobutylene
elastomer, silicates and bentonite. The silicate components are
apparently included to increase the swelling effects of the
compositions, with volumetric swelling increases on the order of
80% and greater for 1 day tests being reported.
Other clay based water swellable compositions are taught for
example in U.S. Pat. Nos. 4,624,982 (Alexander); 4,534,925
(Harriet); 4,534,926 (Harriet); 4,787,780 (Harriet); 4,693,923
(McGroaty); 4,344,722 (Blais); 4,209,568 (Clem); 4,613,542
(Alexander); and 4,501,788 (Clem).
Despite the efforts of the prior art, and in contrast to the
desirability for high volumetric expansion as taught in the above
European application, it has been found highly desirable to provide
a "controlled expansion" water stop material. More specifically, it
has been found that virtually uncontrolled or high expansion water
stop compositions deteriorate and fail under actual usage
conditions. At the same time however, the compositions should be
capable of swelling to a limited degree so that they may adequately
fill the structural gaps or joints into which they are placed to
provide the desired water sealing function.
SUMMARY OF THE INVENTION
These and other objects of the invention are met by the
compositions and methods of preparing same as herein disclosed. The
compositions exhibit desirable "controlled expansion" in that they
will expand rapidly in an amount of at least 5% over a 24-hour
period, but they will not expand greater than about 65% over a
28-day test period. This latter expansion limitation is important
in that it signifies that a water stop made from such compositions
will predictably withstand prolonged moisture contact without
significant deterioration.
Accordingly, the proper blend of initial and delayed expansion has
been found so as to provide adequate, desired initial water stop
expansion so that the composition can expand to occupy a structural
joint or gap to provide adequate water sealing protection. At the
same time due to its limited long term expansion, a durable water
stop product is provided.
More specifically, it has been found that a blend of bentonite
clays, each present in a surprisingly small amount, promotes the
desired swelling balance. This blend of bentonites coupled with an
elastomeric blend of thermoplastic elastomer, cross-linked butyl
rubber and polyisobutylene contributes tack, elasticity and
tenacity to the composition.
Moreover, the desired controlled expansion property is also thought
dependent to at least a limited degree upon the particular method
by which it is prepared. Here, after all of the water stop
composition components have been blended together in a suitable
mixing vessel such as a Sigma blender or Banbury, an additional
mixing or blending for a period of about 55-85 minutes is provided
to assure composition homogeneity.
The invention will be further described in the following detailed
description:
DETAILED DESCRIPTION
Compositions in accordance with the invention include about 10-30
wt % elastomeric component, about 5-10 wt % tackifying agent,
fillers in an amount of 15-30 wt %, plasticizers in an amount of
about 20-40 wt %, and about 25-35 wt % water swellable clay. The
foregoing percentages add up to 100%.
The elastomeric component is carefully selected to combine the
enhanced processability of a thermoplastic elastomer, the
elongation and tenacity attributes of cross-linked butyl rubbers
and the tackiness, softness and flexibility properties of
polyisobutylene. Preferably the cross-linked butyl rubber component
or components comprise about 10-20 wt % of the total elastomeric
component present, preferably about 15 wt %.
The thermoplastic elastomers (TPE) are well-known in the art. For
example, they can comprise styrene/butadiene type copolymers or
styrene-ethylene/propylene type block copolymers. Additionally, the
TPE may include EPDM or EPM rubbers copolmerized with polyolefinic
resins such as polyethylene, polypropylene, poly 1-butene, poly
1-pentene, etc. Suitable thermoplastic elastomers are sold by Shell
under the Shellvis or Kraton trademarks. Also Alcryn brand TPES
available from DuPont may be mentioned as exemplary.
The butyl rubbers are typically at least partially cross-linked and
may for example comprise isobutylene, isoprene and divinylbenzene
terpolymers. Additionally, one preferred butyl rubber comprises
partially cross-linked butyl rubber present in a heavy paraffinic
distillate base to improve processing and serve as a partial
plasticizer. This latter butyl rubber is sold by Hardman Inc. under
the "Kalar" trademark.
As to the butyl rubber terpolymers noted above, "Polysar Butyl XL
10000" may be mentioned as being exemplary. This product is
available from Mobay.
Elastomeric blends in accordance with the invention include
______________________________________ TPE 50-60 wt% of total
elastomer present Cross-linked 10-20 wt % of total elastomer
present Butyl Rubber Polyisobutylene 20-40 wt % of total elastomer
present all of these percentages add up to 100%
______________________________________
Preferably, the TPE blend comprises
______________________________________ TPE 55 wt % Cross-linked 15
wt % Butyl Rubber Polyisobutylene 30 wt %
______________________________________
The butyl rubber component itself preferably includes a blend
of
(1) isobutylene/isoprene/divinylbenzene terpolymer; and
(2) partially cross-linked butyl rubber in a heavy paraffinic
distillate
These two specific butyl rubber components are preferably present
in about a 1:1 wt. ratio. The partially cross-linked butyl rubber
in heavy paraffinic distillate component (2) is softer than the
other (1) butyl rubber component. This blend of (1) and (2) butyl
rubbers provides desirable cold flow stability to the product while
allowing acceptable elasticity and elongation. The polyisobutylenes
are by themselves, well-known in the art. Preferred are the low
molecular weight polyisobutylene homopolymer tackifiers having
molecular weights of about 10,700-11,900 (Staudinger). These are
available from Exxon under the Vistanex LM trademarks.
A variety of fillers may be provided in accordance with the
invention. Non-swelling clays, talc, carbon black, and cellulosic
fibers may be mentioned. In this regard, the inclusion of short
cellulosic fibers in an amount of about 3-5wt % of the total
composition weight imparts mechanical strength.
Ball clay in an amount of about 14-20 wt % is also a desirable
filler as, in addition to filler function, it imparts plasticity
and helps in mixing and processing of the composition. Carbon black
and talc are to be added to the mixture, as desired.
Plasticizers, such as process oils are used in an amount of about
20-40 wt %, based on the weight of the water stop composition to
provide the necessary matrix or continuous phase for
processability. Exemplary process oils include petroleum
aromatic-napthenic oils, napthenic-aromatic oils;
napthenic-paraffinic oils and paraffinic oil. The preferred process
oil is available from Witco under the designation Kendex 0842.
Additionally, other plasticizers such as mineral oil softeners,
vegetable oil softeners, fatty acids, fat and oil, esters and
phosphates may be added.
The water swellable clay utilized is actually a mixture of
"fast-acting" and "slow-acting" bentonite clays. The "fast-acting"
component is a sodium exchanged Texas calcium bentonite clay. These
clays have a Na.sub.2 O content (analysis upon ignition) of greater
than about 1.0% and are herein referred to as a sodium bentonite
clay.
The preferred high swelling sodium bentonite clay used in
accordance with the invention is sold by Southern Clay Products
under the "Astra-Ben 5" designation. This is described as a
hydrated aluminum silicate, bentonite clay, having the following
oxide analysis:
______________________________________ SiO.sub.2 56.8 Al.sub.2
O.sub.3 18.0 Fe.sub.2 O.sub.3 4.2 TiO.sub.2 0.3 CaO 1.5 MgO 3.0
Na.sub.2 O 1.7 K.sub.2 O 0.4 LOI 13.7
______________________________________
As to the lower swelling clay, this is preferably a non-sodium
exchanged calcium bentonite wherein, as can be seen, the Na.sub.2 O
content is less than in the sodium bentonites. These are referred
to herein as calcium bentonite clays. The preferred calcium
bentonite is available under the "Bentolite L-10" designation by
United Clay. Its typical oxide analysis is:
______________________________________ SiO.sub.2 70 Al.sub.2
O.sub.3 17 Fe.sub.2 O.sub.3 1 CaO 2 MgO 3 Na.sub.2 O 0.5 K.sub.2 O
0.3 LOI (980.degree.) 5 ______________________________________
The faster reacting sodium bentonite is present in an amount of
about 40 wt %-50 wt % of the total bentonite mix used for the water
stop composition. Preferably, the sodium bentonite is present in an
amount of about 43-45 wt % based on the total bentonite
present.
In accordance with the invention, exemplary and preferred water
stop compositions are as listed:
______________________________________ Exemplary Elastomeric
Component 10-30 wt % Filler 15-30 wt % Plasticizers 20-40 wt %
Water Swellable Clay 25-35 wt % all of these components add up to
100 wt % Preferred Elastomer Component TPE Cross-linked Butyl
Rubber 18-24 wt % Polyisobutylene Filler 19-27 wt % Plasticizers
26-30 wt % Water Swellable Clay 26-32 wt % all of these components
add up to 100 wt % Most Preferred Elastomer TPE 10-12 Cross-linked
Butyl Rubber 2-4 Polyisobutylene 6-8 Filler Non-swelling clay 14-19
ball clay Talc 1-2 Carbon Black 1-2 Cellulose Fiber 3-4 Plasticizer
Process Oil 26-28 Tall oil Fatty Acid 5-2 Water Swellable Clay
Sodium Bentonite 13-16.5 Calcium Bentonite 13-16.5 all of these
components add up to 100 wt %
______________________________________
It is also apparent that the particular blending or mixing
procedure utilized is important in achieving the goals of the
present invention. In this respect, the ingredients can all be
blended and mixed together in an appropriately sized Sigma blender
or the like. First, the thermoplastic elastomer, and butyl rubber
components are added to the Sigma blender along with the carbon
black, polyisobutylene and tall oil fatty acid plasticizer in the
presence of significant amounts of the process oil plasticizer.
This mixture is then mixed or blended until smooth with additional
process oil, fiber, fast swelling sodium bentonite clay and ball
clay filler being added. The mixture is mixed for about 10 minutes
with an additional amount of process oil, calcium bentonite and
additional ball clay being added. Talc is then added after the
mixing is completed.
In accordance with the invention, once all of the components have
been introduced into the mixture and thoroughly mixed, an
additional mixing step of from about 40-85 minutes, preferably
50-85, is utilized to ensure complete homogeneity of all of the
ingredients. Surprisingly, this extra mixing step has proven quite
important in achieving the "controlled expansion" attributes of the
present invention. The mixing reaction is exothermic. Temperature
is monitored and should be regulated to between about
240.degree.-295.degree. F.
After this second mixing step has occurred, the water stop
composition is then allowed to sit for a period of about 12-48
hours, preferably 24 hours, to stabilize. The thus stabilized mix
is then fed to an extruder wherein, as is conventional in the art,
the composition is extruded in the form of an elongated rope or
tape. Conventionally, a paper backing substrate is coextruded with
the water stop composition along one longitudinally extending side
of the tape or rope. The paper is peeled away prior to usage at the
job site.
The extruded water stop composition is then ready for use to fill a
gap or joint existing between structural units such as concrete
and/or metal building panels. In accordance with the invention, the
water stop desirably expands by an amount of at least 5%,
preferably 5-8%, after 24 hour's immersion in water. In contrast to
many of the prior art extruded water stop tapes or ropes, after a
period of 28 days immersion in water, an expansion of about 35-65%,
preferably 35-50% is experienced. This latter delayed expansion
characteristic is important in that, in actual use, it means that a
durable, integral product is formed that will not be significantly
prone to cracking and separation into discrete particles.
The invention will be explained in conjunction with the appended
examples, which are included as being illustrative of the invention
and should not be construed as limitations.
Example 1--Composition Preparation
Compositions having the following formulations were made in
accordance with the mixing procedures stated above.
______________________________________ Component Composition Number
Identification Component 1 2 3 4 5 6 Supplier
______________________________________ Thermoplastic 11.14 11.08
11.00 10.98 11.08 11.23 A Elastomer X-linked Butyl 1.64 1.63 1.62
1.61 1.63 1.65 B Rubber X-linked Butyl 1.64 1.63 1.62 1.61 1.63
1.65 C Rubber in an oil base Polyiso- 6.19 6.15 6.12 6.10 6.15 6.24
D butylene Ball Clay 18.56 17.42 14.25 16.22 17.42 17.10 E Micro
Talc 1.55 1.54 1.53 1.52 1.54 1.56 F Carbon Black .40 .40 .40 .40
.40 .41 G Cellulosic 3.28 3.26 3.24 3.23 3.26 3.31 H FIbers Fatty
Acid .46 .46 .46 .46 .46 .47 I Plasticizer Process Oil 26.30 26.77
27.22 27.44 26.77 25.74 J Plasticizer Sodium 12.38 13.29 16.27
14.21 13.29 14.04 K Bentonite Clay Calcium 16.46 16.37 16.27 16.22
16.37 16.60 L Bentonite Clay Batch Size 1616 1625 1636 1640 3250
3205 (lbs) Mix Time 29 24 51 43 70 71 After All Components Added
Total Mix 117 86 121 102 159 141 Time Temperature 278 272 290 287
268 276 .degree.F. ______________________________________ A =
Styreneethylene/propylene block copolymer Shellvis 40/50; Shell B =
Crosslinked butyl terpolymer rubber; isobutylene, isoprene,
divinylbenzene terpolymer; Polysar Butyl XL 10000, available Mobay
C = Crosslinked butyl rubber in heavy paraffinic distillate base;
Kalar 5263, Hardman Inc., Belleville, NJ D = Vistanex LM, Exxon
Chemical; polyisobutylene MW, Staudinger 10,700-11,900 E = Ball
Clay, available United Clays Inc., Gleason, Tennessee F = Micro
Talc magnesium silicate hydrate; Montana Talc G = Carbon Black
Huber Corporation H = Cellulose Fibers; Central Fiber Corp.,
Wellsville, Kansas I = Tall Oil Fatty Acid Mixture of mostly Oleic
& Linoleic Acid, Union Camp. J = Process Oil; Kendex 0842;
Witco Chemical K = Sodium bentonite clay Astroben4 Southern Clay
Products, Gonzales, Texas L = Calcium bentonite clay Bentonite L10;
Southern Clay Products, Gonzales, Texas
Example 2--Volumetric Expansion
Extruded tapes were made from the water stop compositions
identified in Example 1. The extruded tapes were immersed in water
for the requisite time periods, and tape volume increases were
recorded. The following results were obtained.
Results are given in terms of average values obtained from four
roll samples of each of the compositions.
__________________________________________________________________________
Days Composition S.P. Grav. 1 4 7 14 21 28 35 50
__________________________________________________________________________
Extruded Shape 3/4" .times. 1" (3 days) 5 1.3125 7.49 12.02 20.83
32.06 36.87 43.13 48.86 6 1.3475 5.79 9.90 17.16 24.54 30.56 36.21
41.38 Extruded Shape .60" .times. 3/4" 5 1.31 8.04 14.81 26.32
40.63 49.88 59.39 66.31 6 1.34 6.80 12.20 22.11 33.01 41.67 48.58
57.39 Extruded Shape 7/8" .times. 13/8" 5 1.30 5.56 10.37 16.01
24.03 30.64 36.24 41.34 6 1.35 5.45 8.41 13.37 20.11 25.15 31.13
36.95
__________________________________________________________________________
*indicates signs of cracking
Example 3--Volumetric Expansion
Another series of compositions were prepared in accordance with the
procedures detailed above. Extruded tapes made from these
compositions were tested for volumetric expansion upon immersion in
water for the requisite time test periods as per Example 2. The
following results were obtained. Again, results are given as
average values derived from four roll samples of each of the
compositions.
__________________________________________________________________________
Days Composition S.P. Grav. 1 4 7 14 21 28 35 50
__________________________________________________________________________
1 1.265 2.36 7.02 9.89 12.82 17.89 23.59 25.14 26.46 2 1.292 2.57
7.20 10.68 15.58 21.48 26.26 27.32 32.47 3 1.298 4.81 13.27 19.78
31.22 42.88 42.78* -- -- 4 1.29 4.90 14.3 24.28 40.28 52.66 63.25*
-- --
__________________________________________________________________________
*Signs of Cracking
DISCUSSION OF EXAMPLES
Based upon the above tests, compositions in accordance with the
above will exhibit the desired controlled volume expansion of about
5-8% after 24 hours and between about 35-65% expansion after 28
days provided that process mixing-time after addition of the last
formulation component is regulated to between about 50-85 minutes.
Additionally, although Applicant is not to be bound to any
particular theory of operation, the specific combination of high
swelling sodium bentonite clay and lower swelling calcium bentonite
clay in the formulation appears to provide a surprising balance
between desirable initial high volume increase and controlled 28
day expansion. Based upon the data presently available, composition
No. 6 is presently preferred.
The skilled artisan will appreciate that modifications may be made
to the specific composition and process embodiments specifically
described above without departing from the true spirit and scope of
the invention as defined in the appended claims.
* * * * *